<title>Adf.ly decoder</title>
<?php

function request( $url ) {
    $ua = 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1712.4 Safari/537.36';
    if ( !preg_match( '/^[a-zA-Z0-9\/]+$/', $url ) )
        return false;

    $ch = curl_init();
    curl_setopt_array( $ch, array(
        CURLOPT_FAILONERROR => true,
        CURLOPT_FOLLOWLOCATION => false,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 10,
        CURLOPT_USERAGENT => $ua,
        CURLOPT_URL => 'http://adf.ly/' . $url
    ) );
    $data = curl_exec( $ch );
    curl_close( $ch );

    if ( preg_match( "#var ysmm = '([a-zA-Z0-9+/=]+)'#", $data, $matches ) ) {
        $final = $url = decode( $matches[1] );
        // check for redirects
        $ch = curl_init();
        curl_setopt_array( $ch, array(
            CURLOPT_FAILONERROR => true,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HEADER => true,
            CURLOPT_NOBODY => true,
            CURLOPT_TIMEOUT => 10,
            CURLOPT_USERAGENT => $ua,
            CURLOPT_URL => $url
        ) );
        $data = curl_exec( $ch );
        if ( preg_match_all( '/Location:\s*(.+)\s*$/im', $data, $matches, PREG_SET_ORDER ) ) {
            $last = array_pop( $matches );
            $final = trim( $last[1] );
        }

        return array( $url, $final );
    }

    return false;
}

function decode( $ysmm ) {
    $left = '';
    $right = '';
    for ( $i = 0; $i < strlen( $ysmm ); $i++ ) {
        if ( $i % 2 == 0 ) {
            $left .= $ysmm[$i];
        } else {
            $right = $ysmm[$i] . $right;
        }
    }
    return substr( base64_decode( $left . $right ), 2 );
}

if ( isset( $_GET['url'] ) && $_GET['url'] ) {
    // strip out beginning (everything up to last slash)
    $stripped = '';
    $slashes = explode( '/', $_GET['url'] );
    $stripped = array_pop( $slashes );

    list( $url, $final ) = request( $stripped );
    if ( $url ) {
        echo '<p>Your URL is <a href="' . $url . '">' . $url . '</a>';
        if ( $url != $final ) {
            echo ' (<a href="' . $final . '">' . $final . '</a>)';
        }
        echo '</p>';
    } else {
        // try 2 parts
        $stripped = array_pop( $slashes ) . '/' . $stripped;
        list( $url, $final ) = request( $stripped );
        if ( $url ) {
            echo '<p>Your URL is <a href="' . $url . '">' . $url . '</a>';
            if ( $url != $final ) {
                echo ' (<a href="' . $final . '">' . $final . '</a>)';
            }
            echo '</p>';
        } else {
            echo '<p>Adf.ly URL not found</p>';
        }
    }
}
?>
<form method="GET">
Adf.ly URL to decode: <input type="text" name="url" /> <input type="submit" value="Go" />
</form>